This invention relates to lasers employing solid-state crystalline materials in which the active ion is an integral part of the compound of the crystal, not a dopant, and has a concentration more than 20 times higher than in doped glass or conventional, doped crystalline lasers.
It has been recently appreciated that active ion concentration in a solid-state dielectric crystal laser can be substantially increased if the anions sufficiently shield the active ions from each other. An example is that disclosed in U.S. Pat. No. 3,813,613, of H. G. Danielmeyer and one of us, H. P. Weber, issued May 28, 1974, and assigned to the assignee hereof. That success implies that the ordering of the elements within the crystal is sufficiently strict that the active ions, e.g., neodymium, do not come too close to each other. The resulting high concentrations permissible have yielded surprisingly small lasers and are expected to lead to still smaller lasers and, in some applications, to improvements in pumping efficiently and lasing threshold.
As a consequence of the foregoing development, further effort has been directed toward finding other compounds in which the active ion, such as neodymium (Nd.sup.3.sup.+) is an integral part of the compound forming the crystal lattice.